Production of Ethanol from Municipal Solid Waste of India and Nepal

Abstract

The increasing generation of municipal solid waste and energy crisis is posing various problems in developing countries. The major portion of municipal solid waste generated in developing countries mainly consists of organic waste. Apart from currently used disposal techniques like composting, anaerobic digestion, RDF, landfilling, etc., ethanol production from organic fraction of MSW could be a promising source of energy generation and waste management. Very limited researches have been conducted on utilizing municipal solid waste to ethanol production in case of Nepal and India. The feasibility of ethanol production was studied at lab scale using food waste generated at Greater Noida, India. Food wastes were collected, dried, and crushed to produce ethanol in this study. Principally, two experiments were carried out in series (i.e., hydrolysis and fermentation). Varying acid concentration and temperature were considered for optimization in hydrolysis. The maximum reducing sugar yield obtained was 32.63 g/100 g of dry food waste at 7.5% acid concentration at 135 °C. The ethanol yield was 13.78 g/100 g of dry food waste. Both Monod equation and Luedeking–Piret model were fitting the fermentation results obtained in the study. For Monod equation, the value of Ks and µmax were found to be 26.19 g/l and 0.08 h−1, respectively. The product formation of fermentation was found to be growth associated as per Luedeking–Piret model. As per the theoretical calculations, 13,414 L/d and 329,756 L/d of ethanol can be produced from MSW of Kathmandu Valley and Delhi, respectively. It can be concluded that ethanol can be produced efficiently by controlled fermentation techniques from municipal wastes using Saccharomyces cerevisiae. Production of ethanol from a free resource like organic portion of municipal solid waste is doubtlessly an attractive disposal option from environmental point of view. However, detailed cost–benefit analysis of ethanol production option with other disposal options is necessary to assess economic viability and its application at larger scale.